Method and apparatus for desktop air conditioning

ABSTRACT

A method and apparatus for desktop air conditioning provides conditioned air to individuals sitting at a desk. A raised floor air delivery system provides a plenum having conditioned air under the raised floor upon which the individual and their desk sit. Small ducts extend vertically up from the floor to the underneath side of the desk where they are connected to a desktop diffuser. The desktop diffuser directs air from the plenum generally horizontally across a top of the desk toward the chest and face of the individual. The desktop diffuser is low profile so as not to interfere with the surface of the desktop and its aesthetics.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a method and apparatus for providing desktop air conditioning. More particularly, this invention relates to a diffuser for use in combination with a raised floor air distribution system, wherein the diffuser is received in an opening in a desktop and provides a low profile air distribution component.

Providing conditioned air to a room or rooms within a building having a raised floor air distribution system is known in the art. FIGS. 1 and 2 illustrate a prior art raised floor air distribution system that was modified to provide personalized or individually controllable distribution of conditioned air to individual desks. While it is important that any air distribution system adequately control the temperature of the rooms as a whole, such may not be sufficient to accommodate the individual needs of persons in the rooms. Thus, while the room may be of a desired overall temperature, individuals in the room may have different desires as to the temperature in their specific locations. This is of particular concern in office buildings where individuals are asked to sit for long periods at a time at a specific location, such as at a desk and/or in a cubicle.

The prior art system illustrated in FIG. 1 or 2 attempted to accommodate the individual desires of a person sitting at a desk by providing a desk with a flow of conditioned air through a duct which would deliver the conditioned air out the front of the desk beneath the desktop. Presumably, the individual at the desk would have the ability to control the amount of air flowing through the duct underneath the desk and therefore the amount of air coming out of the desk. Unfortunately, this prior art system had several shortcomings that prevented widespread adoption. For example, the conditioned air was provided to an individual's lap or waist. Generally, however, when an individual is hot and desiring a cooler temperature, it is their upper body or torso that is in need of cooling, not their waist or legs. Additionally, because the air coming out of the duct underneath the desk is cooler, the air would have a tendency to drop down to the individual's feet, thereby making their feet cold and not cooling their core mass or upper body. Additionally, the provision of the large ductwork directly underneath the desktop where the user sits makes it impossible to provide a drawer in the opening where the user's legs reside while seated at the desk.

FIG. 3 illustrates an alternate prior art embodiment that attempted to address the shortcomings of the system of FIGS. 1 and 2. The prior art system illustrated in FIG. 3 discloses a desktop air conditioning system that makes use of a pair of air terminals or towers that extend or protrude upwardly from the desktop. A control box is also positioned on the desktop to permit the occupant to control the temperature and volume of air flowing through the system.

In a cooling mode, conditioned air would be drawn up from a plenum underneath the floor upon which the user's chair sits. The conditioned air would pass through the ductwork and be forced out the front of the desktop units through manually adjustable louvers that are akin to the louvers found in automobile air distribution systems. The individual air terminals included knobs that control the volume of air through the face of the unit.

If a warmer temperature is desired, the user may use the control panel to turn on a radiant heat panel adjacent the user's feet. This is because it has generally been found that when a user is cold, it is their feet that require heating. As such, the radiant panel by their feet emits warmer air. In this mode, the system can also intake the warmer air by the floor up into the ductwork and disperse it out the individual air distribution towers.

While the system illustrated in FIG. 3 represented an improvement over the prior art system illustrated in FIGS. 1 and 2, the prior art system in FIG. 3 also has numerous shortcomings that have prevented widespread adoption of the system. Initially, the system is quite complex and is therefore expensive to manufacture and install. The control panel that sits on the desk must be connected to a number of items in order to control the various functions of the unit. In addition to having to have the control panel on the desktop, the occupant must also deal with having to have the two air distribution towers protruding up from the desktop. In a cubicle-type environment, desktop space is often at a premium and having to have three large components sitting on the desktop is often undesirable.

The method and apparatus of the present desktop air distribution system overcomes these and other drawbacks by providing a system which is low profile, simple to operate, and significantly less expensive to install. The system includes preferably, a pair of flexible tubular ducts that extend upwardly from openings in a floor tile of a raised floor air distribution system. The ducts engage with an underneath side of a low profile desktop diffuser. The diffuser includes a plurality of fins therein which direct the flow of air through an upper surface of the diffuser and out of the diffuser in a direction that is generally along the upper surface of the desk. In this manner, the air is directed to the occupant's torso and chest to provide cooling where desired. In one embodiment, the diffuser is a variable volume diffuser that includes a pair of plates that cooperate to control the volume of air flowing through the diffuser. The diffuser presents a low profile on the desktop and takes up a minimal amount of desk surface area.

Further objects, features and advantages of the present invention over the prior art will become apparent from the detailed description of the drawings which follows, when considered with the attached figures.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The features of the invention noted above are explained in more detail with reference to the embodiments illustrated in the attached drawing figures, in which like reference numerals denote like elements, in which FIGS. 1-16 illustrate several possible embodiments of the present invention, and in which:

FIG. 1 is a side elevation view of a prior art system for providing conditioned air to individual desks using an under floor air distribution system with a plenum;

FIG. 2 is a perspective view of an individual desk outfitted with the prior art system of FIG. 1;

FIG. 3 is a side elevation view of an alternate prior art system for providing conditioned air to individual desks using an under floor air distribution system with a plenum;

FIG. 4 is a side elevation view of a system for providing conditioned air to individual desks using an under floor air distribution system with a plenum in accordance with an embodiment of the present invention;

FIG. 5 is a perspective view of a desk of FIG. 4 outfitted with an embodiment of the present invention;

FIG. 6 is an enlarged side elevation view of one of the desks of FIG. 4 with a user seated at the desk;

FIG. 7 is a perspective view of an alternate embodiment of a desktop air conditioning system of the present invention;

FIG. 8 is an enlarged perspective view of an embodiment of an adjustable desktop diffuser of the present invention with a portion of a desktop cut away for clarity;

FIG. 9 is a fragmentary exploded perspective view of the diffuser of FIG. 8 with a portion thereof cut away for clarity;

FIG. 10 is a bottom perspective view of the diffuser of FIG. 8 with a portion of a stationary plate cut away for clarity;

FIG. 11 is a bottom plan view of the diffuser of FIG. 8 with a movable plate in an open position;

FIG. 12 is a bottom plan view of the diffuser of FIG. 8 with the movable plate in a partially closed position;

FIG. 13 is a bottom plan view of the diffuser of FIG. 8 with the movable plate in a closed position;

FIG. 14 is a top plan view of the diffuser of FIG. 8 with the movable plate omitted;

FIG. 15 is an enlarged fragmentary side elevation view of the diffuser of FIG. 14 with a portion cut away for clarity; and

FIG. 16 is a fragmentary perspective view of an embodiment of a constant volume diffuser of the present invention with a portion of the diffuser cut away for clarity.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in more detail and initially to FIG. 4, numeral 10 generally designates a desktop air conditioning system arranged in accordance with an embodiment of the present invention. The system 10 is implemented in a building 12 having walls 14 and structural floors 16. The structural floors 16 can be concrete slabs and one structural floor 16 may be a ceiling to help define a room 18. Often the lower surface of a structural floor 16 that is used as a ceiling is hidden from view by a false or a dropped ceiling (not shown).

The building 12 preferably also has a raised floor air distribution system 20. The raised floor air distribution system 20 includes a plurality of floor tiles 22 that are supported above the structural floor 16 to create an operating floor 24. The floor tiles 22 are supported by a plurality of adjustable pedestals or stands 26. The operating floor 24 and the structural floor 16, along with a portion of the walls 14, cooperate to define a plenum 28 between the operating floor 24 and the structural floor 16. An air handling unit (not shown) provides conditioned air to the plenum 28 underneath the operating floor 24. The plenum 28 is kept at a positive pressure when compared to the pressure of the ambient air in the room 18. As such, the conditioned air will attempt to move from the plenum 28 into the room 18 when permitted to do so. A floor terminal 30 may be provided in a floor tile 22 to accommodate the passage of air from the plenum 28 into the room 18, as illustrated by the arrows 32.

In the illustrated embodiment, the system 10 is preferably coupled with the plenum 28 by way of a floor unit 34. The floor unit 34 may be of a similar size as the floor terminal 30 such that the floor unit 34 may be placed in a standard opening of a floor tile 22 for a floor terminal 30. Alternatively, and as illustrated, the floor unit 34 may be of a smaller size to decrease the size of the opening through the floor tile 22 into which the floor unit 34 is received. The floor unit 34 permits conditioned air from the plenum 28 to pass therethrough into the desktop air conditioning system 10, as discussed in more detail below.

The desktop air conditioning system 10 includes at least one supply duct 36 and a desktop diffuser 38. As illustrated in FIGS. 5 and 7, the desktop air conditioning system 10 may be implemented with a pair of supply ducts 36 coupled with a pair of desktop diffusers 38. As illustrated in FIG. 5, the floor unit 34 may take the shape of a rectangular metal plate or lid for covering an opening in a floor tile 22 and having a pair of openings therethrough to permit the ducts 36 to be in fluid communication with the plenum 28. In the embodiment illustrated in FIG. 5, the floor unit 34 is provided with a pair of cylindrical collars (not shown) that extend upwardly from an upper surface of the plate like portion of the floor unit 34. These collars provide a structural portion of the floor unit 34 onto which ends of the supply duct 36 may be received and to which they may be coupled. As illustrated in FIG. 7, a floor unit 34 may be omitted and the supply ducts 36 may be directly coupled with floor tiles 22 around openings therein. Additionally, the supply ducts 36 may be rigid, as illustrated in FIG. 7, or flexible tubing, as illustrated in FIG. 5. Similarly, the supply duct 36 may have any type of configuration, beyond just the cylindrical configuration illustrated.

The desktop air conditioning system 10 is preferably implemented in a desk 40 having a work surface or desktop 42 with a generally horizontal upper surface 44. An opening 46 is provided in the desktop 42 to receive a portion of the desktop diffuser 38, as illustrated in FIG. 8. FIG. 8 also illustrates that the diffuser 38 is coupled with an upper end 48 of the supply duct 36. A lower end 50 of the supply duct 36 is coupled with a floor unit 34 or directly with a floor tile 22.

Turning now to FIGS. 8-10, the desktop diffuser 38 will now be described in more detail. Preferably, the diffuser includes a grille portion 52 and a body portion 54. In the illustrated embodiment where the desktop diffuser 38 is round in appearance, the grille portion takes the shape of a circular disc-like member and the body portion takes the shape of a cylindrical member, such as a section of a pipe or tube. The grille portion 52 has an upper surface 56 that is also the upper surface of the desktop diffuser 38. The upper surface 56 is preferably flat or planar, for reasons that will be discussed below, and oriented in a generally horizontal position. The body portion 54 is preferably coupled with a lower surface 58 of the grille portion 52 adjacent an upper or proximal edge 60 of the body portion 54 such that the body portion 54 depends downwardly from the grille portion 52, as illustrated in FIGS. 8 and 9.

The grille portion 52 has an outer periphery 62 of a first circumference and the body portion 54 has an outer surface 64 that defines a second circumference. As illustrated in FIG. 10, the first circumference of the grille portion 52 is larger than the second circumference of the body portion 54 such that an outwardly depending lip 66 is created about the proximal edge 60 of the body portion 54. The lip 66 includes an annular ring of the lower surface 58 of the grille portion 52. When the desktop diffuser 38 is received in the opening 46 in the desktop 42, the lower surface 58 of the grille portion 52 that is part of the lip 66 rests on the upper surface 44 of the desktop 42 about the opening 46 to support the diffuser 38 in the opening 46, as illustrated in FIG. 8. The grille portion 52 includes a plurality of fins 68 which cooperate to define air channels 70 through which air may exit the diffuser 38 through the upper surface 56.

The raised floor air distribution system 20 with its floor terminals 30 provide general control of the temperature in the room 18. The desktop air conditioning system 10 of the present invention supplements those efforts by providing individualized, personalized, and customizable conditioned air to individual users 72 to help accommodate the different temperature desires of occupants of the building 12. In that regard, the desktop air conditioning system 10 can be used by the user 72 in FIG. 6 to provide cooler air from the plenum 28 when the user 72 feels hot. To best cool the user 72, the conditioned air that passes through the diffuser 38 should be primarily directed at the user's upper body or torso 74. To accomplish this, the fins 68 are angled with respect to the upper surface 56 to direct the flow of air, as represented by the arrows 76 in FIG. 6, primarily along the upper surface 44 of the desktop 42. To accomplish the desired generally horizontal throw of the desktop diffuser 38, the fins 68 were designed accordingly.

As illustrated in FIG. 15, the fins include an angled upper surface 78 and an angled lower surface 80. The angled upper surface 78 preferably slopes downwardly from the upper surface 56 an angle α and the angled lower surface 80 slopes downwardly with respect to the upper surface 56 and angle β. The angle α is preferably between 15°-55° and, in one embodiment, is approximately 35°. The angled β is in the range of 25°-65° with respect to the upper surface 56, and, in one embodiment, is approximately 48°. The angled lower surface 80 joins a downwardly facing surface 82 that provides a ledge 84 that is generally parallel to the upper surface 56. The ledge 84 helps direct air coming up the lower angled surface 80 of the fin into a generally horizontal throw.

The fins 68 also preferably include an upper vertical wall 86 and a lower vertical wall 88. The fins also include a lower surface 90 at the bottom of the angled lower surface 80 and a ridge 92 at a bottom of the angled upper surface 78.

As illustrated in FIG. 14, the fins may also be arranged in an arcuate shape to spread the air flow out in a wide direction radially from the diffuser 38. As will be appreciated from the plan view in FIG. 14, the air would be disbursed across an angle of less than 180°, with the majority of the throw being directed along a centerline of the diffuser 38 which would fall along a rib 94 that separates the two groups of air channels 70. The arcuate fins 68 create arcuate air channels 70. As illustrated in FIG. 14, the fins can be arranged in a concentric orientation about a point 96 adjacent and edge of the grille portion 52.

To provide the user 72 with some control of the volume of air flowing through the diffuser 38, the diffuser 38 in FIGS. 8-13 is a variable air volume diffuser. As such, the diffuser 38 includes a volume control mechanism 98. In the illustrated embodiment, the mechanism includes a movable plate 100 and a stationary plate 102. The plates 100, 102 take the shape of disc-like objects and have a plurality of radially aligned pie shaped openings therethrough, thereby providing a wagon wheel appearance. The plates 100, 102 are received in the body portion 54 and coupled with a hub 106 in the center of the lower surface 58 of the grille portion 52 along the rib 94 by a screw 108 that passes through the center of the plates 100, 102. As illustrated in FIG. 9, the movable plate 100 is placed closest to the grille portion 52 and includes a user engageable tab 110 that is generally perpendicular to an upper surface 112 of the movable plate 100. The tab 110 extends upwardly through an arcuate slot 114 in the grille portion 52 of the diffuser 38. The user 72 may then move the tab 110 side to side to rotate the movable plate 100.

The stationary plate 102 can be held in place by a number of different ways. In one embodiment, an inner surface 116 of the body portion 54 includes a plurality of longitudinally extending ridges 118 thereon. The stationary plate 102 has a corresponding set of notches 120 in its outer periphery 122 that align with and cooperate with the ridges 118 on the inner surface 116 of the body portion 54, as illustrated in FIG. 10. The movable plate 100 has a smaller diameter than the stationary plate 102 so that the outer edge of the movable plate 100 fits within and does not engage with the ridges 118.

In FIG. 11, the movable plate 100 is in an open or first position, where the openings 104 in the movable plate 100 are aligned with the openings 104 in the stationary plate 102. In this position, the maximum amount of air is allowed to pass through the desktop diffuser 38. In FIG. 12, the user 72 has rotated the movable plate 100 by way of the tab 110 such that a portion of the openings 104 in the stationary plate 102 are covered by portions of the movable plate 100. In this position, the air flow has been reduced by an amount somewhat less than half. FIG. 13 illustrates the movable plate 100 in a second or closed position where none of the openings 104 in the movable plate 100 are aligned with the openings 104 in the stationary plate 102. As such, the volume control mechanism 98 operates to prevent the flow of air through the diffuser 38.

FIG. 16 illustrates an alternate embodiment of the desktop diffuser 38. In this embodiment, the desktop diffuser 38 is a constant volume diffuser and does not include a volume control mechanism 98. The user 72 could still control the amount of air blown in their direction by rotating the diffuser 38 in the opening 46 in the desktop 42 such that the centerline of the throw pattern, represented by the rib 94, points away from them. The farther the user rotates the diffuser away from pointing at them, the lower the volume of air being directed to the user, and therefore the user will notice a decrease in cooling.

In one embodiment of the invention, the supply ducts 36 are 4″ flexible ducts and the outer surface 64 of the body portion 54 has a circumference that is sized for receipt in the ducts. In this embodiment, the floor unit 34 is 5″×10″ and is received in an opening in a 24″×24″ floor tile 22. The plenum 28 is kept at a pressure of 0.02-0.1″ water gauge compared to the standard pressure in the room 18. This results in a volume of air of approximately 15 cubic feet per minute being directed to the user 72 at a velocity of less than 50 feet per minute. A velocity of zero to 50 feet per minute has been found beneficial and a volume of 5-50 cubic feet per minute has also been found beneficial. The majority of the air exiting the diffuser should fall between 0°-45° angle from the desktop 42.

Accordingly, the desktop diffuser 38 is well designed to provide a low profile desktop air conditioning delivery mechanism. Preferably, the upper surface 56 of the diffuser 38 projects up from the desktop 42 less than one-half of one inch. More preferably, the upper surface 56 of the desktop diffuser 38 protrudes from the desktop approximately less than two-tenths of one inch.

Many variations can be made to the illustrated embodiment of the present invention without departing from the scope of the present invention. Such modifications are within the scope of the present invention. For example, the diffusers can be square in shape and the air channels be straight across as opposed to arcuate. This would provide for a more uni-directional throw of the air across the desktop. Another modification would be to permit volume control of the constant volume diffuser of FIG. 16 by placing an object on top of the upper surface 56 of the diffuser 38. The user 32 could move the object back and forth across the upper surface of the diffuser to control the amount of air passing therethrough. It should be noted that while the diffuser was described as having a grille portion coupled with a body portion, the diffuser 36 may be cast as a single unitary member. Other modifications would be within the scope of the present invention.

From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects hereinabove set forth together with the other advantages which are obvious and which are inherent to the method and apparatus. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the invention.

Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative of applications of the principles of this invention, and not in a limiting sense. 

1. A method of providing desktop air conditioning in a building having a raised floor air distribution system, the system including an air handling unit for providing conditioned air and a raised floor with a plurality of floor tiles supported above a structural floor to define a plenum, and a desk having a desktop, the conditioned air being supplied to the plenum to keep it at a positive pressure variance when compared to a room above the raised floor, the method comprising: providing at least a first supply duct leading upwardly from and in fluid communication with the plenum, whereby conditioned air from the plenum may pass through the raised floor and up the supply duct; and providing a desktop diffuser, the diffuser having a lower portion that is coupled with the first supply duct and an upper portion that is supported by the desktop, wherein the diffuser is positioned in a opening in the desktop, wherein the diffuser includes a grille with a plurality of fins, wherein the fins define air channels through which the conditioned air may pass from the supply duct, through the diffuser and into the room through the air channels, wherein the grille includes an upper surface, wherein the upper surface is generally parallel to the desktop, wherein the air channels provide passages through the upper surface, and wherein the fins are angled with respect to the upper surface of the grille at a degree sufficient to direct air from the diffuser in a direction that is generally along the desktop.
 2. The method of claim 1, wherein the diffuser includes a body portion, wherein the body portion is generally cylindrical, and wherein the body portion extends downwardly from the grille.
 3. The method of claim 2, wherein the fins are generally arcuate in shape, whereby the passages through the upper surface are generally arcuate in shape.
 4. The method of claim 3, wherein the grille is a generally planar circle having an outer circumference, wherein the outer circumference of the grille is greater than an outer circumference of the generally cylindrical body, thereby creating a lip around the diffuser, and wherein the lip of the diffuser rests on the desktop.
 5. The method of claim 1, wherein the diffuser is a low profile diffuser such that the diffuser sticks up from the desktop less than one inch.
 6. The method of claim 5, wherein the diffuser sticks up from the desktop less than one quarter of one inch.
 7. The method of claim 1, wherein the diffuser further includes an air volume adjustment mechanism having a stationary plate and a movable plate, wherein the plates are positioned adjacent one another, below the grille, and generally parallel to the upper surface, wherein the plates include a plurality of openings therein, and wherein the movable plate is selectively movable between an open position, where at least one of its openings is aligned with at least one of the openings in the stationary plate, and a closed position, where none of the openings in the movable plate are aligned with the openings in the stationary plate.
 8. The method of claim 7, wherein the movable plate includes a user engageable tab that protrudes upwardly from and is generally perpendicular to an upper surface of the movable plate, wherein the grille includes an arcuate slot there in, and wherein a portion of the tab is received in the slot, whereby a user may move the movable plate via engagement with the tab.
 9. The method of claim 1, wherein the diffuser includes a body portion that extends downwardly from the grille, wherein the body portion is received in the opening in the desktop, wherein the body portion has a central longitudinal axis, wherein the central longitudinal axis is generally vertical and perpendicular to the desktop.
 10. The method of claim 9, wherein the body portion is generally cylindrical and wherein the diffuser may be rotated in the opening in the desktop about the central longitudinal axis to alter the direction of air flow out of the diffuser.
 11. A desktop diffuser for use in an opening in a top of a desk as part of a desktop air conditioning system, the diffuser comprising: a grille portion having a plurality of fins which define air channels through which conditioned air may pass, wherein the grille includes a generally planar upper surface that is generally parallel to the top of the desk when the diffuser is received in the opening, wherein the air channels pass through the upper surface, and wherein portions of the fins are angled with respect to the upper surface of the grille such that a majority of air passing through the air channels and out of the diffuser is made to flow in a direction that is closer to parallel to the upper surface than it is to perpendicular to the upper surface; and a body portion, wherein the body portion extends downwardly from a lower surface of the grille.
 12. The diffuser of claim 11, wherein a portion of the lower surface of the grille extends outwardly beyond the body portion to create a lip and wherein the diffuser is supported by the lip resting on the top of the desk when the diffuser is received in the opening.
 13. The diffuser of claim 12, wherein the lower surface of the grille that extends outwardly beyond the body portion to create the lip is less than half of one inch from the upper surface of the diffuser.
 14. The diffuser of claim 11, wherein the fins include an upper angled surface and a lower angled surface, wherein the upper angled surface faces the upper surface, and wherein a plurality of the upper angled surfaces are angled downwardly with respect to the upper surface between 15°-55°.
 15. The diffuser of claim 14, wherein a plurality of the upper angled surfaces are angled downwardly with respect to the upper surface approximately 35°.
 16. The diffuser of claim 14, wherein the lower angled surface faces downwardly and wherein a plurality of the lower angled surfaces are angled downwardly with respect to the upper surface between 15°-55°.
 17. The diffuser of claim 11, wherein the fins include an upper angled surface and a lower angled surface, wherein the fin further includes a ledge having a downwardly facing surface, wherein the ledge extends outwardly from an upper end of the lower angled surface, and wherein the downwardly facing surface of the ledge is generally parallel to the upper surface of the grille.
 18. The diffuser of claim 11, wherein the air channels provide passages through the upper surface, wherein the fins are generally arcuate in shape, and wherein the passages through the upper surface are generally arcuate in shape.
 19. The diffuser of claim 18, wherein the passages are concentric in shape from a point on the upper surface adjacent an edge of the upper surface.
 20. The diffuser of claim 11, wherein the diffuser is a variable volume diffuser further comprising: a stationary plate and a movable plate, wherein the plates are positioned adjacent one another, below the grille, and generally parallel to the upper surface, wherein the plates include a plurality of openings therein, and wherein the movable plate is selectively movable between an open position, where at least one of its openings is aligned with at least one of the openings in the stationary plate, and a closed position, where none of the openings in the movable plate are aligned with the openings in the stationary plate.
 21. The diffuser of claim 20, wherein the movable plate includes a user engageable tab that protrudes upwardly from and is generally perpendicular to an upper surface of the movable plate, wherein the grille includes an arcuate slot there in, and wherein a portion of the tab is received in the slot, whereby a user may move the movable plate via engagement with the tab.
 22. A low profile, variable volume, desktop diffuser for use in an opening in a top of a desk as part of a desktop air conditioning system having a conditioned air supply duct, the diffuser comprising: a generally circular grille portion having a lower surface and a generally planar upper surface, the grille having a plurality of stationary fins which cooperate to define air channels through which conditioned air may pass, wherein portions of the fins are angled with respect to the upper surface of the grille such that a majority of air passing through the air channels and out of the diffuser is made to flow at an angle that is less than 45° to the upper surface, the grille having an outer circumference of a first dimension; a generally cylindrical body portion connected to and depending downwardly from the lower surface, wherein the body portion has an outer circumference of a second dimension, wherein the outer circumference of the body portion is less than the outer circumference of the grille portion such that an annular lip is formed having downwardly facing desktop engaging surface that is generally parallel to the upper surface of the grille, whereby the diffuser is supported in the opening in the desk by the lip, wherein the diffuser is rotatable in the opening; and means for controlling the volume of conditioned air flowing through the diffuser.
 23. The diffuser of claim 22, wherein the cylindrical body portion is tubular in nature and includes an inner wall surface having at least one longitudinally extending ridge thereon, the means for controlling the volume of conditioned air flowing through the diffuser comprising: a stationary plate and a movable plate, wherein the plates are generally circular in nature, wherein the stationary plate has a larger circumference than the movable plate, wherein circumference of the stationary plate is less than a circumference of the inner wall, wherein the stationary plate includes a notch in an edge thereof, wherein the ridge is received in the notch to hold the stationary plate in place, wherein the plates are positioned adjacent one another, below the grille, and generally parallel to the upper surface, wherein the plates include a plurality of openings therein, and wherein the movable plate is selectively movable between an open position, where at least one of its openings is aligned with at least one of the openings in the stationary plate, and a closed position, where none of the openings in the movable plate are aligned with the openings in the stationary plate.
 24. A method of providing desktop air conditioning comprising: providing a desk having a generally horizontal and planar desktop with an opening therein; providing a low profile diffuser having an upper surface with a plurality of passages therein through which conditioned air may pass and a support surface facing in a direction opposite of the upper surface; receiving the diffuser in the opening of the desk such that the support surface engages the desktop; and coupling a supply duct to a portion of the diffuser, whereby conditioned air may pass from the supply duct, through the diffuser, and out the upper surface of the diffuser.
 25. The method of claim 24, wherein the upper surface of the diffuser is less than half of one inch above the desktop when the diffuser is received in the opening. 